---
id: kb-2026-00015
title: SQL (Structured Query Language)
schema_type: TechArticle
category: computer-science
language: en
confidence: medium
last_verified: '2026-05-28'
created_date: '2026-05-22'
generation_method: ai_structured
ai_models:
  - claude-opus
derived_from_human_seed: true
conflict_of_interest: none_declared
is_live_document: false
data_period: static
completeness: 0.82
atomic_facts:
  - id: fact-computer-science-sql-01
    statement: "ISO/IEC 9075-1:2023 is an ISO standard in the SQL family, covering the SQL framework."
    source_title: "ISO/IEC 9075-1:2023 Information technology - Database languages SQL - Part 1: Framework"
    source_url: https://www.iso.org/standard/76583.html
    confidence: medium
  - id: fact-computer-science-sql-02
    statement: "PostgreSQL 17 documentation presents SQL as the language used to define, query, and manipulate data in PostgreSQL."
    source_title: PostgreSQL 17 Documentation
    source_url: https://www.postgresql.org/docs/17/
    confidence: medium
  - id: fact-computer-science-sql-03
    statement: "Codd's paper 'A Relational Model of Data for Large Shared Data Banks' is a foundational paper for relational database systems."
    source_title: A Relational Model of Data for Large Shared Data Banks
    source_doi: 10.1145/362384.362685
    confidence: medium
known_gaps:
  - "This article is a concise SQL primer and does not compare every vendor dialect or release-specific feature."
  - "Implementation details vary across PostgreSQL, MySQL, SQLite, Oracle Database, SQL Server, and other systems."
disputed_statements: []
primary_sources:
  - title: "ISO/IEC 9075-1:2023 Information technology - Database languages SQL - Part 1: Framework"
    type: standard
    year: 2023
    institution: ISO
    url: https://www.iso.org/standard/76583.html
  - title: PostgreSQL 17 Documentation
    type: documentation
    year: 2026
    url: https://www.postgresql.org/docs/17/
    institution: PostgreSQL Global Development Group
  - title: A Relational Model of Data for Large Shared Data Banks
    authors:
      - Codd, E.F.
    type: academic_paper
    year: 1970
    doi: 10.1145/362384.362685
    institution: IBM / Communications of the ACM
secondary_sources: []
updated: '2026-05-28'
---

## TL;DR

SQL is the standardized language family used to define, query, and manipulate data in relational database systems. The public evidence here is intentionally narrow: it maps SQL standardization to ISO, practical SQL usage to PostgreSQL documentation, and relational database foundations to Codd's relational-model paper.

## Core Explanation

SQL sits at the interface between applications and relational database systems. In day-to-day use, SQL statements create schema objects, insert and update rows, query tables, join related data, aggregate results, and control transactions.

The language is standardized through the ISO/IEC 9075 family, but implementations also provide dialect-specific extensions. PostgreSQL, MySQL, SQLite, Oracle Database, SQL Server, and other systems therefore share a recognizable SQL core while differing in syntax details, optimizer behavior, functions, and administrative features.

Relational databases are historically connected to E. F. Codd's relational model, which separated logical data relationships from physical storage details. SQL is not identical to relational theory, but it became the dominant practical language for working with relational database systems.

## Further Reading

- [ISO/IEC 9075-1:2023 SQL framework](https://www.iso.org/standard/76583.html)
- [PostgreSQL 17 Documentation](https://www.postgresql.org/docs/17/)
- [A Relational Model of Data for Large Shared Data Banks](https://doi.org/10.1145/362384.362685)

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